The present invention relates generally to an exposure apparatus that projects and exposes a mask pattern onto a substrate via a projection optical system, and a device manufacturing method that uses the exposure apparatus to manufacture various devices, such as a semiconductor chip and a liquid crystal panel, and more particularly to an exposure apparatus that fills the fluid in the space between the projection optical system and substrate, and exposes the substrate using the light via the fluid, and a device manufacturing method using such an exposure apparatus.
An exposure apparatus is required to use a shortened exposure wavelength and an increased numerical aperture (“NA”) of a projection optical system along with the finer processing to the integrated circuit. Since the shortened wavelength has limits of a type of glass material used for the projection optical system, an immersion exposure has been proposed as a method to substantially shorten the exposure wavelength to expose the substrate using the light via the fluid filled in the space between the projection optical system and the substrate. The immersion exposure method includes a method (or a so-called local fill system) that arranges a fluid supplying/recovering nozzle around a lens at the top of the projection optical system, and fills the fluid only in the space between the wafer and the lens at the top of the projection optical system (see, for example, International Publication No. 99/49504 pamphlet), and a method for immersing the entire wafer in the fluid (see, for example, Japanese Patent Application, Publication No. 10-303114).
International Publication No. 99/49504 pamphlet discloses that the fluid controlled to the predetermined temperature is flowed between the projection optical system and the wafer. However, if a temperature difference occurs between the fluid and the wafer, a local thermal strain generates on the wafer, a change of the refractive index of the fluid lowers the resolution, and the yield of the exposure apparatus deteriorates consequently.
On the other hand, the method of Japanese Patent Application, Publication No. 10-303114 that immerses the entire wafer in the fluid solves a problem of the temperature difference between the fluid and the wafer to some extent. However, this method makes the structure of the exposure apparatus large and complex, and causes the fluid surface to swell as the stage moves, deteriorating the positioning performance of the stage, and dispersing the fluid.